Metal straightening apparatus and method



E. F. CREAGER METAL STRAIGHTENING APPARATUS AND METHOD Filed April 1, 1959 Jgn. s, 1963 2 Sheets-Sheet 1 Jan. 8, 1963 E. F. CREAGER 3,072,173

METAL STRAIGHTENING APPARATUS AND METHOD Filed April 1, 1959 2 Sheets-Sheet 2 I coouua cu ave g HEAT RANGE l ISOTHERMAL PE.

QUE ucH AIR COOLING CURVE ROOM TEMPERATURE 'INVENTOR. EARL F. CREAGER BY 4 A We 7% F Q9 m ATTORNEY awaits Patented Jan. 8, i963 l1 fire had 3,072,173 METAL STRATGHTENING APPARATUE AND METHOID Earl F. Creager, Grown Point, Ind, assignor to The Anderson Company, a corporation Endiana Filed Apr. 1, I959, Ser. No. 803,493 (llairns. (ill. 153-39) This invention relates to shaping metal bodies which have become warped or distorted, and more particularly it is directed to straightening metal bodies which have become distorted in the tempering operation or during mechanical treatment thereof, such as in rolling or machining.

One of the problems inherent in the manufacture of long screws is distortion. Residual strains are set up as a result of cold-forming the steel. These strains are relieved in heat-treating, and distortion accompanies their relief. During the quenching process, however, additional strains are set up, which result from unequal rates of cooling. They are caused by temperature gradients which characterize the geometry of the design.

A principal object of this invention is to overcome the above-noted problems and to provide a simple and 8fllClIlt method and apparatus for reshaping distorted metal bodies.

It is another object of this invention to provide a method and apparatus for the rapid straightening of marquenched rods.

It is still another object of this invention to provide an improved apparatu including a form or jig to which the body to be straightened may be clamped during the sharp ing or straightening treatment.

It is a still further object of this invention to provide an apparatus for yieldingly, but firmly, clamping a distorted body against a form or jig corresponding to the correct shap for said body.

Further objects and advantages of this invention will appear as the following specification progresses, taken in connection with the accompanying drawings, wherein:

FIGURE 1 is a plan view of my improved straightening apparatus, the operating handle for the clamping fingers being broken away;

FIGURE 2 is a transverse cross-sectional view of the apparatus taken along line 22 of FIGURE 1;

FIGURE 3 is a transverse section taken along line 3-3 of FIGURE 1;

FIGURE 4 is a detail view taken on line -i-4 of FIG- URE 1;

FIGURE 5 is a perspective view of the jig or form against which the articles to be straightened are clamped; and

FIGURE 6 is a graph of the marternpering cooling curve of a typical steel in relation to time and temperature.

While my invention is susceptible of embodiment in many different forms, I have shown in the drawings and will herein describe in detail one such embodiment, with the understanding that the present disclosure is to be considered but an exemplification of principles of the invention and is not intended to limit the invention to the embodiment illustrated. The scope of the invention will be pointed out in the appended claims.

The fundamental principles of heat-treating steel remain much as they were in the days of Tubal Cain. The scientific aspects of these fundamental principles, however, have been recently determined. They have been depicted graphically in the T.T.T.-curves, relating to time, temperature, and transformation. These were first published in 1930, and they now belong to the realm of the public domain.

The solution to the problem of eliminating distortion in screws is dependent upon the information supplied by the T.T.T.-curves. Simply stated, it is this: The rate of cooling from the austenetizing temperature (above 1365 F.), to the start of the transformation to martensite (approximately 400 F.), is critical to the transformation. After the transformation has once started, the cooling rate is no longer critical. The completion of the martensitic transformation is dependent upon continuous cooling to approximately F.

After the screw has been rapidly cooled (quenched) to an equalized temperature of approximately 400 F., it is removed from the quenching medium and placed in an apparatus for shaping distorted metal objects. It is securely clamped in the apparatus until the screw has cooled continuously to 170 F. or below. This is followed by tempering to the required physical properties.

Steel in its solid state is in either one of two phases. The first is the low temperature condition, usually running from about 400-l500 F wherein the alloying elements are in a state of solid solution. This is known as the ferritic phase. Upon continuously cooling from the austenitic (at or above 1360 F.) temperature at rates known and followed in the art, a temperature is reached at which the metal starts to transform to the martensite form, the hard constituent. The temperature at which austenite starts to turn into martensite is well known for each alloy content of steel.

The transformation of austenite to martensite is accompanied by a marked and measurable increase in volume. Therefore, surfaces-such as thin areas-which are characterized by sharp temperature gradients are susceptible to distortion. This distortion is caused primarily by the difference in the time required for thin and thick portions of a body to reach the transformation temperature.

A well-known procedure is to provide a quenching medium at a temperature substantially corresponding to the start of the transformation temperature to martensite and to transfer the steel in the austenite phase thereto, and thereafter rapidly reduce the temperature of the steel to the transformation stage, in accordance with the curve of FIGURE 6. This permits the differences in temperature which are caused by said temperature gradients to equalize at the start of the transformation. The foregoing practice is called marquenching. Once the transl martensite starts. In the case of modified 1095 steel, the

start of transformation to martensite occurs at 390 F. and the completion is at 170 F.

In accordance with the process of this invention, when the steel body to be shaped or straightened cools to the state of incipient transformation-that is to say, when it cools substantially to the isothermal quench line of FIG- URE 6 (in the case of modified steel 1095 for example, to substantially 390 F.), the steel body is immediately transferred to a jig or straightening fixture to which it is clamped for completion of the transformation phase during at least a substantial portion of the final cooling curve depicted in FIGURE 6. The steel thus shaped or straightened may be transferred immediately to a tempering (draw) bath or oven and reheat to a temperature that will yield the desired physical properties. I have found that upon removal from the jig a steel body shaped or J3 straightened as above indicated retains the precise shape of the jig or form, with no inherent tendency to distortion. The process is applicable for truing or shaping steel bodies during pristine stages, such as an adjunct to foundrying, and the operation of rolling, cutting or stamping steel while hot. The process is, of course, equally applicable for correcting cold bodies which have been distorted in handling, machining or otherwise. In the latter case the body must be again heated until it reaches the austenitic state.

My invention relates to an apparatus especially suited for the practice of the process described above. Referring now to FIGURES 1 and 2 of the drawing, the shaping apparatus includes a rigid fiat metal strip iii having an upturned arm 11 integral with each end thereof. A shaft 12 bridges the space between said arms and is pivoted to the arms by aligned pintles 13. Each pintle has a head 14 contacting the outer wall of one of said arms, and a neck portion 15 journaled in a bearing opening formed in its respective arm, with the inner end of each pintle threaded into the contiguous ends of the shaft. A plurality of plates 16 are fastened, such as by spot welding, to the bottom wall of strip 10 in spaced parallel relation to each other, and project laterally from one edge of the strip. The plates 16 thus define the base of the apparatus, while the projecting ends 17 of the plates define a support for the shaping jig or channeled form 18. One of the plates 16, preferably the center one, has a portion 19 extending beyond the opposite side edge of strip 10 which extension is upturned at 21 to cooperate with a compound lever system to be described hereinafter.

Shaft 12 has a series of spaced sockets 21 formed therein along a straight line, and a series of fingers 22. of spring material are fixed at one end in said sockets and project radially from said shaft. Upon rotation of shaft 12, the

several fingers will be turned to the solid-line position of FIGURE 2 to yieldingly but firmly press down upon and clamp objects or bodies, such as a rod or rods 23, positioned in the several grooves 24 of jig 18. The resilience of fingers 22 also enables the apparatus to receive objects presenting limited variation in cross section. To reinforce shaft 12 against the strain of said clamping operation, I provide one or more arcuate straps 24, each of which is secured by screws 25 to the upper end of a bearing block 26 (FIGURE 3). Each bearing block has a semicircular bearing surface 27 for supporting the under portion of shaft 12. The lower end of each block 26 is fastened to strip 10 by welding or the like.

Shaft 12 may be rotated to and from clamping position by the compound linkage system best shown in FIG- URE 2. The system includes a primary or actuating link 28 which is integral with and extends from one end of a lever arm or handle 29 at an angle of approximately 30 degrees. A second link 30 has one end rigidly fixed to shaft 12 and has its opposite end pivotally connected at 31 to the free end of primary link 28. One end portion of a pair of spaced parallel links 32 is pivoted by pin 33 to the juncture of the primary link 28 and the handle 29. The opposite end portions of links 32 are pivoted at 34 upon the end of a thrust pin 35. Pin 35 is adjustably fixed in an opening in arm 20. The pin 35 is threaded so as to receive nuts 36 thereon on opposite sides of arm 2t) for effecting said adjustment. In FIGURE 2 the dotted-line position of fingers 22 and the link system represent the open or unclamped position of the fingers. Upon swinging lever 29 downwardly, the primary link 28 is brought into general alignment with parallel links 32, creating a toggle effect toward the end of the stroke between the primary link 28 and the parallel links 32 which, acting through link 3t), firmly presses the latch fingers 22 against the elements 23 that are being straightened.

In the specific embodiment shown, the form or jig 18 is in the nature of an elongate block (FIGURE 5) having one or more synclinal or V-grooves 24 formed therein.

Each groove is adapted to receive one of the metal bodies,

rods or pieces to be trued up or straightened. Jig 18 is not fastened to base plates 16 and, therefore, when the fingers are withdrawn from the clamping position of FIG- URE 2, the jig may be readily removed for placement of rods thereon, after which it is repositioned on plates 16. Where the objects to be trued or straightened are received directly from the foundry, rolling mill, or the like in the hot state, it is contemplated that jigs will be kept nearby so that the objects may be placed thereon at once and the jigs quickly transferred to the clamping means herein described.

While the jig shown is primarily intended for straightening metal rods, it is to be understood that the shape of the jig may be varied to conform to the contour to whichthe particular body under treatment is to be corrected or shaped. I

Having thus described my invention, it is obvious that various modifications may be made in the same without departing from the spirit of the invention; and, therefore, I do not Wish to be understood as limiting myself to the exact form, construction, arrangement and combination of parts herein shown and described.

I claim:

1. Apparatus for straightening distorted metal rods comprising a rigid strip, a series of spaced plates fixed to the lower surface of said strip and projecting in parallel relation from one edge thereof, said plates constituting a base for the apparatus, the projecting portions constituting a support for an elongate jig, said jig resting on said projecting portions and having at least one V-groove extending parallel to said strip for receiving said rods, a: shaft pivoted to said strip, a plurality of stiff fingers CX tending transverse to and being rigid with said shaft and adapted upon rocking of the shaft to yieldingly but firmly press said rods into said groove, and means for rocking said shaft.

2. The apparatus as defined in claim 1 wherein the means for rocking said shaft includes a linkage system including a toggle arrangement for applying load upon said fingers and latching the system under stress.

3. Apparatus for straightening distorted elongate metal bodies and the like comprising a strip having upturned ends, a series of spaced plates fixed to the bottom surface of said strip and projecting in parallel relationship from one edge thereof, one of said plates having a portion extending from the opposite edge of said strip and ter minating in an upturned arm, said plates constituting a base for the apparatus and the projecting portions con stituting a support on which a jig may rest, said jig beingpositioned on said projections and being formed witlr grooves defining the correct geometry for said bodies, a shaft arranged between and rockably mounted on said upturned ends of said strip, a plurality of fingers extending transverse to said bodies in a common plane and being rigid with said shaft, said fingers adapted to press said rods into said grooves, and means for rocking said shaft including a manually operable linkage system reacting between said upturned arm and said shaft.

4. Apparatus for shaping distorted metal objects including a base, a jig adapted to be positioned on said base, said jig having a contoured area defining the correct shape for said objects, a rock shaft mounted uport said base, a plurality of spaced fingers each fixed at one end to said rock shaft to move into position to clamp said object upon rocking of said shaft in one direction, and means to rock said shaft including a manually operabie linkage system, said system including a link rigidly connected at one end to said shaft, a second link pivoted at one end to a thrust member rigid with said base, and an actuating link pivoted at each end to the free ends. of said first-mentioned links, said actuating link having an integral handle lever extending from one end thereof at an ang on the order of 30 degrees.

5. App atus for holding elongate metal bodies during; heat treating comprising in combination: a base having a.

shaft pivotally mounted thereon, said base adapted to receive an elongate jig thereon, said jig having at least one receiving portion adapted to receive elongate metal bodies in a position substantially parallel to said shaft, said shaft having a plurality of transversely extending elongate resilient fingers disposed along the length of said shaft and overlying said receiving portion and adapted to lie juxtaposed said elongate metal body and adapted upon rocking of said shaft to resiliently urge said elongate 10 metal body into said receiving means, and linkage means operatively associated with said shaft and adapted to rock said shaft.

References Cited in the file of this patent UNITED STATES PATENTS Miner Feb. 25, 1913 Evans Oct. 26, 1926 Beans Nov. 26, 1935 P-urnell June 29, 194-3 Scott Jan. 1, 1957 Adair et al. May 13, 1958 Gogan Mar. 24, 1959 FOREIGN PATENTS Switzerland May 1, 1920 Switzerland June 2, 1919 

1. APPARATUS FOR STRAIGHTENING DISTORTED METAL RODS COMPRISING A RIGID STRIP, A SERIES OF SPACED PLATES FIXED TO THE LOWER SURFACE OF SAID STRIP AND PROJECTING IN PARALLEL RELATION FROM ONE EDGE THEREOF, SAID PLATES CONSTITUTING A BASE FOR THE APPARATUS, THE PROJECTING PORTIONS CONSTITUTING A SUPPORT FOR AN ELONGATE JIG, SAID JIG RESTING ON SAID PROJECTING PORTIONS AND HAVING AT LEAST ONE V-GROOVE EXTENDING PARALLEL TO SAID STRIP FOR RECEIVING SAID RODS, A SHAFT PIVOTED TO SAID STRIP, A PLURALITY OF STIFF FINGERS EXTENDING TRANSVERSE TO AND BEING RIGID WITH SAID SHAFT AND ADAPTED UPON ROCKING OF THE SHAFT TO YIELDINGLY BUT FIRMLY PRESS SAID RODS INTO SAID GROOVE, AND MEANS FOR ROCKING SAID SHAFT. 